Wind powered apparatus, also known as windmills or wind turbines, have been used for a variety of applications including pumping water, grinding grain, and generating electricity. For all of these applications, it is desirable to improve the performance of the apparatus.
For horizontal axis wind turbines (HAWT's), it is important that the apparatus includes a means for orienting it into the wind. Although one method of accomplishing this is by adding a tail to the turbine rearward of the blades, a tail can be exposed to turbulence in the wake of the blades and be slow to react to minor changes in wind direction. It would therefore be desirable to improve performance by providing a method for operating the apparatus that includes orienting the apparatus into the wind, desirably without the use of a tail.
A problem encountered by wind turbines is the need to prevent unacceptably high rotational speeds during extreme wind conditions. Although one method of accomplishing this is by adding a brake to the apparatus, this introduces mechanical complexity and a potential failure mode for the apparatus. It would therefore be desirable to improve performance by providing a method for operating the apparatus that includes limiting the maximum rotational speed of the blades.
Another problem encountered with electricity generating wind power apparatus is the relatively high minimum speed that is required before electricity generation can begin without stalling the apparatus. It would be desirable to improve performance by lowering the minimum wind velocity required for a given electrical output from the apparatus.
Yet another problem encountered with many commercial scale wind turbines is the lack of ability to rotate completely (360°) about their vertical axis to accommodate changes in wind direction. Although it would be desirable to provide such complete rotation, factors such as the twisting of electrical power wires typically render this option unavailable. A related side effect is that a turbine at the extremity of its rotational movement can sometimes lack the ability to maintain orientation into the wind and, as a result, can become locked in a non-power generating position without the ability to turn back in to the wind. It would therefore be desirable to provide a wind powered apparatus capable of complete 360° rotational movement about its vertical axis.
It is desirable to achieve these improvements in a low cost and reliable manner.
The need therefore exists for an improved wind powered apparatus that addresses some or all of these deficiencies in the art and/or achieves some or all of the above-noted desirable improvements.